Determining in-band optical signal-to-noise ratio in polarization-multiplexed optical signals using signal correlations
AssigneeViavi Solutions Inc.
InventorFred L. Heismann
Life of this patent
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Abstract
A method and apparatus for determining in-band OSNR in optical information signals, e.g. in polarization-multiplexed QPSK and higher-order M-ary QAM signals, are disclosed. A correlation measurement of the signal amplitude or power at two distinct optical frequencies of the signal may be used to determine the in-band optical noise in the signal. A measurement of the signal power may be used to determine the OSNR based on the determined in-band noise.
Claims13
An apparatus for determining an optical signal-to-noise ratio of a modulated optical signal comprising a plurality of wavelength channels, the apparatus comprising:
- a spectrum analyzer to measure an optical power spectrum of the modulated optical signal;
- a frequency selective splitter to select first and second portions of the modulated optical signal at first and second predetermined optical frequencies, wherein the first and second predetermined optical frequencies are separated by a non-zero frequency interval;
- a measuring unit to measure a time-varying parameter comprising at least one of:
- time-varying optical amplitudes and phases;
- and
- time-varying optical power levels of the first and second portions of the modulated optical signal;
- and
- a signal processor to:
- determine a correlation between the time-varying parameters of the first and second portions of the modulated optical signal;
- and
- calculate the optical signal-to-noise-ratio from the correlation of the time-varying parameters and the power spectrum of the modulated optical signal.
An apparatus, comprising:
- a spectrum analyzer to measure an optical power spectrum of a modulated optical signal;
- and
- a signal processor to:
- determine a correlation between time-varying parameters of first and second portions of the modulated optical signal;
- and
- calculate an optical signal-to-noise-ratio from the correlation of the time-varying parameters and the optical power spectrum of the modulated optical signal.
Dependencies are inferred from the claim text.